trane air handler

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  #1  
Old 01-02-13, 05:48 PM
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trane air handler

I have a trane air handler that is reading 10 volts instead of 24 volts on the thermostat from red to white, but the red to green is 28 volts, red to yellow is 28 volts, and red to blue (common) is 28 volts???
The heat will only come on when the thermostat is set to the on position and not the auto, does anyone have any ideas on this one?
 
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Old 01-02-13, 05:57 PM
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1st.... You are not checking voltage properly. We will come back to this.
The heat will only come on when the thermostat is set to the on position and not the auto
ARE you talking about the fan switch on and auto? Is this a new thermostat or recently new?
 
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Old 01-02-13, 06:02 PM
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Yes I am talking about the fan position set to on and set to heat the fan will run along with the heat strips but, when it you change to auto and heat nothing will come on. I get voltage accordingly to post above red to white 10 volts, red to green 28 volts, red to yellow 28 volts, and red to blue (which is supposed to be common) is 28 volts.


Thanks,

Mike
 
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Old 01-02-13, 06:05 PM
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Sorry it is also a new thermostat
 
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Old 01-02-13, 06:12 PM
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THANK YOU! It is a new thermostat..... make sure it is set for ELECTRIC heat and not GAS heat. When set to ELECTRIC heat the thermostat will cycle the fan with a call for heat. When set to GAS heat it does NOT cycle the fan with a call for heat as it is controlled by the furnace.
 
  #6  
Old 01-02-13, 06:22 PM
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The thermosat is set to heat, again the confusion is the 10 volts from red to white on thermostat, when I am getting 28 volts everywhere else, therefore the heat is not coming on in the auto and heat position. This unit worked last year, but all of sudden this year it is not working accordingly.


Thanks,

Mike
 
  #7  
Old 01-02-13, 06:28 PM
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NO! The problem is the setting of the thermostat! You are not checking voltage properly! The heat is coming on in auto, the FAN is not! How new is the thermostat? What is the make and model number of the thermostat?

With a call for heat on an electric furnace you should have 0V or so between R and W and R and G. The PROPER WAY to check what is happening is to check voltage between W and C and G and C with a call for heat.
 
  #8  
Old 01-02-13, 06:29 PM
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R = 24vac hot
c = 24vac common
w = heating relay
y = cooling contactor
g = fan realy
 
  #9  
Old 01-02-13, 06:38 PM
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Yes the wiring is as you described on the thermostat, no the heat is not working in the auto position along with the heat setting, it only works when the fan is turned to the on position.

The thermostat is a top tech tt-n-701



Thanks,

Mike
 
  #10  
Old 01-02-13, 06:54 PM
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http://www.toptechparts.com/resource...701_in_man.pdf

Please verify page 7 (electric heat) and remember to RESET after any changes made.
 
  #11  
Old 01-02-13, 07:02 PM
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Ok thank you I will try tomorrow and let you know the update.

Thanks,

Mike
 
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